igi2] SKINNER— CREATININE AND CREATINE 159 



of NH 3 in the fertilizer mixture becomes 136, or an increase of only 

 36 per cent. In other words, in the absence of creatinine from the 

 cultures, the nitrate (8 ppm.) caused an average increase of 59 per 

 cent in the various cultures; in the presence of the creatinine 

 (50 ppm.) the nitrate (8 ppm.) caused an average increase of only 

 36 per cent. It appears, therefore, that plants supplied with 

 creatinine do not respond so markedly to added nitrate, thus seem- 

 ing to indicate that the plant can utilize this nitrogenous compound 

 for plant syntheses. 



■ 



Effect of creatinine on absorption of fertilizer salts 



The foregoing discussion has shown clearly the influence of 

 creatinine on growth and its effect in cultures containing no nitrates. 

 There remains to be discussed the effect of the creatinine on the 

 removal of nutrients from the solution during the growth of 

 the plant. 



Mention has been made already of the fact that the concentra- 

 tion differences produced by the growth of the plants in the various 

 cultures were determined by making an analysis for nitrates at the 

 termination of every three-day change, and of the phosphates and 

 potassium on a composite of the solutions from the four changes. 

 It is thus possible to compare the results obtained under the so- 

 called normal conditions without the creatinine and under the 

 conditions where 50 ppm. of creatinine were present in the solution. 



The sum total of P 2 5 , NH 3 , and K 2 removed from solution by 

 the growing plants in the cultures containing all three of these 



milligrams 



milligrams 



The figures show the total 



of plant nutrients to be slightly less in the creatinine set, although 

 the green weight in this set was 9 per cent greater than in the normal 

 set. The examination of the results for the three constituent 

 separately as given below shows that the phosphate and potash were 

 slightly greater than normal, as is demanded by the larger growth, 

 whereas the nitrate is considerably less than in the normal set. 



Phosphate.— The amount of phosphate stated as F 2 5 removed 

 from the total number of solutions during the experiment was 364 

 milligrams for the normal cultures and ^8^ milligrams for the cul- 



